Integrate
1
4
2
(-1+
2
b
)
π1+3
2
b
+(-1+
2
b
)Cos[2alpha-2θe]-2
2
b
1+
2
b
+(-1+
2
b
)Cos[2alpha-2θe]
Csc[alpha-θe]+
πSin[alpha-θe]1-
b
2
b
--1+
2
b

2
Sin[alpha-θe]
-1+
2
b
,{alpha,0,θe},Assumptions{0<b<1,0≤θe<π}